From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B21D9C433F5 for ; Sat, 23 Oct 2021 12:53:18 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 6F98F604DC for ; Sat, 23 Oct 2021 12:53:18 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 6F98F604DC Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.microsoft.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date: Message-ID:From:References:Cc:To:Subject:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=C1Wyh9oHIV12+/P/Ci75HvDg/L9PxcIC8c2pkxQAsbQ=; b=Z6T34tc7vclbQFgXHsc7kaSlpe GqgDohrBX9OnSaxk60yjXhr3vLMPwRVz3J2JQ5RDQCB2E+o++2xv/MbUoXnUpSg9qezzOol+37U7m pwnISsnxL06vkgMLZ9nC6k7VN5NzAzLR11v2LpvtlX+ajGNEBCdedrPwyVjzwKBZ7FiAqjHBwvvJl eQEfZ9Xhkbr7qGWLClJ4rpAY5Fs5KYup04NRly3Si2Pxn0O7ZzQ8Dg9udodA4eJJAvErdRKSWHNtG B87raiNvXkS6TGGUfWFeh3dtlCccN+A9/QGeWN+VNSPYre0VO5u4LUVRYoLK84QNXbC4McMxEjIAI mF2xDGAQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1meGVB-00CmF5-Ng; Sat, 23 Oct 2021 12:51:57 +0000 Received: from linux.microsoft.com ([13.77.154.182]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1meGV7-00CmEa-SA for linux-arm-kernel@lists.infradead.org; Sat, 23 Oct 2021 12:51:55 +0000 Received: from [192.168.254.32] (unknown [47.187.212.181]) by linux.microsoft.com (Postfix) with ESMTPSA id 66C032063658; Sat, 23 Oct 2021 05:51:51 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 66C032063658 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1634993512; bh=RdTHdq2wYecLPNsH3yc13xGJJ4ejMJTIX+ByLhv3VSk=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=fY62T29GRFOFNOt69w9wl8U9BzW+9fyDV+vhzs44GQvTi70UrYD6MfnSabWGKR+eF fl8jnJLiXFyvQWlr7rRomiaeyBvPpbj9FxVN2hxxT/if4csTIGPvHo6YEqhyIBPD+z 8zF5sTnRY8ZsP/ucSA6Mv/f0NE5qlt+Od8U843co= Subject: Re: [PATCH v10 04/11] arm64: Make return_address() use arch_stack_walk() To: Mark Rutland Cc: broonie@kernel.org, jpoimboe@redhat.com, ardb@kernel.org, nobuta.keiya@fujitsu.com, sjitindarsingh@gmail.com, catalin.marinas@arm.com, will@kernel.org, jmorris@namei.org, linux-arm-kernel@lists.infradead.org, live-patching@vger.kernel.org, linux-kernel@vger.kernel.org References: <20211015025847.17694-1-madvenka@linux.microsoft.com> <20211015025847.17694-5-madvenka@linux.microsoft.com> <20211022185148.GA91654@C02TD0UTHF1T.local> From: "Madhavan T. Venkataraman" Message-ID: <9986ddf4-d992-ffd8-7032-a18fdbdb7bb1@linux.microsoft.com> Date: Sat, 23 Oct 2021 07:51:50 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: <20211022185148.GA91654@C02TD0UTHF1T.local> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211023_055154_005872_144085F1 X-CRM114-Status: GOOD ( 24.42 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 10/22/21 1:51 PM, Mark Rutland wrote: > On Thu, Oct 14, 2021 at 09:58:40PM -0500, madvenka@linux.microsoft.com wrote: >> From: "Madhavan T. Venkataraman" >> >> Currently, return_address() in ARM64 code walks the stack using >> start_backtrace() and walk_stackframe(). Make it use arch_stack_walk() >> instead. This makes maintenance easier. >> >> Signed-off-by: Madhavan T. Venkataraman >> --- >> arch/arm64/kernel/return_address.c | 6 +----- >> 1 file changed, 1 insertion(+), 5 deletions(-) >> >> diff --git a/arch/arm64/kernel/return_address.c b/arch/arm64/kernel/return_address.c >> index a6d18755652f..92a0f4d434e4 100644 >> --- a/arch/arm64/kernel/return_address.c >> +++ b/arch/arm64/kernel/return_address.c >> @@ -35,15 +35,11 @@ NOKPROBE_SYMBOL(save_return_addr); >> void *return_address(unsigned int level) >> { >> struct return_address_data data; >> - struct stackframe frame; >> >> data.level = level + 2; >> data.addr = NULL; >> >> - start_backtrace(&frame, >> - (unsigned long)__builtin_frame_address(0), >> - (unsigned long)return_address); >> - walk_stackframe(current, &frame, save_return_addr, &data); >> + arch_stack_walk(save_return_addr, &data, current, NULL); > > This looks equivalent to me. Previously the arguments to > start_backtrace() meant that walk_stackframe would report > return_address(), then the caller of return_address(), and so on. As > arch_stack_walk() starts from its immediate caller (i.e. > return_address()), that should result in the same trace. > > It would be nice if we could note something to that effect in the commit > message. > Will do. > I had a play with ftrace, which uses return_address(), and that all > looks sound. > Thanks a lot! >> >> if (!data.level) >> return data.addr; > > The end of this function currently does: > > if (!data.level) > return data.addr; > else > return NULL; > > ... but since we initialize data.addr to NULL, and save_return_addr() > only writes to data.addr when called at the correct level, we can > simplify that to: > > return data.addr; > OK. I will make this change. > Regardles of that cleanup: > > Reviewed-by: Mark Rutland > Tested-by: Mark Rutland > Thanks a lot! > I'll continue reviewing the series next week. > Great! Madhavan _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel